feat(create-turbo): `--no-git` flag (#10720)
### Description
As an edge case, some users don't want Git to be initialized when they
set up a Turborepo. This flag removes `.git` when we're done with our
work so the user can handle it themselves.
### Testing Instructions
Tests have been added and tried it manually.
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Co-authored-by: Chris Olszewski <chris.olszewski@vercel.com>
